1. Technical Field of the Invention
The present invention relates to a technology for imparting a stringed instrument's resonance effect to an audio signal.
2. Description of the Related Art
Some stringed instruments such as guitars are equipped with a pickup which uses a piezoelectric element to output vibration propagated from a string as an electrical signal. The electrical signal is amplified and output through a speaker, allowing the user to listen to the guitar's sound at an amplified volume. However, the sound, which is output as the electrical signal generated through the piezoelectric element, includes almost none of the resonance components generated by the body or the like of the guitar. Accordingly, sound reproduced from the electrical signal gives the listener a different impression from sound generated by playing an acoustic guitar or the like.
Japanese Patent Application Publication No. 2005-24997 describes a technology in which convolution operation is performed on the electrical signal through a Finite Impulse Response (FIR) filter to add a resonant sound of the body to the signal.
In the technology described in Japanese Patent Application Publication No. 2005-24997, when convolution operation is performed so as to reproduce a resonant sound of the body of a guitar of a certain model, the generated sound is heard as if the resonant sound of the body is added to the sound, unlike when convolution operation is not performed. However, the generated resonant sound is heard as being totally different from a resonant sound of the body of a guitar of a specific model, which the user desires to reproduce. This difference becomes more noticeable when convolution operation is performed on an electrical signal output from a guitar of a different model from a guitar of a model whose resonant sound the user desires to reproduce.